Ravenloft as a plane

[Mistmaster]

In my Campaign, I intend revamp Ravenloft as full-fledged material plane.
It's Key features will be close proximity to Shadow Plane and to Negative Energy plane, and an unique transition plane, the Mist;
The promotion of the Demiplane of Dread to full-fledged plane is a consequence to my approach to the Dark Powers as a cluster of embrional supreme Deities; Since one of the major themes of my campaign is a reorganization of the multiverse, the responsable of this reorganization, the Supreme of Supremes, once discovered the Demiplane, he gave the Dark Powers more understanding and control on theyr power; They provided then, to rework theyr play-ground, following the Supreme One directives (but conserving some of theyr favored tools.)
My question now is: what I keep, what I discard? Planar insulation needs to go, because free Prime-materials travel is another theme of the campaign; The Mist stays, of course, but for the rest? Dark Lords, Curses, Fear and Madness, Power Checks, Magic Alterations, those are all things I needs to check on, to adapt them to my new Ravenloft.

[Cam]

I think a lot depends upon how much canon history of Ravenloft you want to keep in the backstory of your setting. Are you having Ravenloft move into the Prime Material after Strahd and Barovia get sucked in; after the Grand Conjunction; after lots of NPCs get sucked in from other worlds in the Prime Material; etc.? If so, then you've got to ask yourself what is happening to the parts of the Prime Material that were the sources of all those Ravenloft NPCs. Are they disappearing, to be replaced only by domains from Ravenloft? Or are they going to exist together? And if they're going to exist together, will all the domains from Ravenloft replace landmasses on planets that are already part of the Prime Material, form their own planets/continents, or something different? For me, I would need answers to those sorts of questions before being able to figure out if Darklords tied to the land make sense, thematically, as part of your Prime Material plane. I think you could make any of it work logically -- if the Dark Powers are going to be gods who can manipulate the Prime Material, then you could have them impose the same metaphysics on it that have governed the Demiplane of Dread for all these years -- it's just a question of what you think makes the world cohesive and interesting. I imagine you want there to be a number of major differences, otherwise you wouldn't go to the trouble of changing the setting this much, right?

I recommend looking at Masque of the Red Death if you have not done so yet. It's about envisioning a Ravenloft-like setting on a more-or-less Prime Material planet. It has some good suggestions on how you might modify some of the features of Ravenloft that you mentioned to have them make sense for this type of setting.

Another thing you might consider doing is looking up some of the discussion threads and author interviews on this site that talk about what the Darklords would do if they gained freedom of mobility around the demiplane (as a result of Azalin and the Gentleman Caller). If you get rid of the concept of the lord being bound to the land, then I think how your lords move around and try to influence neighboring domains would be something to focus on in your campaign.

Good luck!

[Mistmaster]

Thank you, you have been very usefull.

[Mistmaster]

I have given it a thought, and I think Ravenloft is going to keep all those things and people it got from other worlds of the material plane; As any real world do, It will have continents (four, the Core, the Verdurous Lands, the Desert Lands, and the Cold Lands, plus the many islands.) The Great Change happened right after the Conjunction; False history is now retconned as true, and false gods exist really somewhere in the great wheel.
Dark Lords aren't imprisoned any more, but theyr special powers works only in theyr domains, immortality and eternal youth included. Strahd is still a Powerfull Vampire arcanist, out of Barovia, but he loose his others Dark Lord Powers and can be killed as any vampire can. His curse still stand.
Plus, Dark Lords cant any more close the border of theyr damains in an absolute way; This mean that venom-immune peoples will be able to leave Barovia even without Strahd permission and cold protected people can leave Adam's domain even if he doesn't appreciate it. However, now they can pursue.